Pro-euro Cabinet ministers are expecting the gag that has prevented them from arguing their case in public to be lifted as part of the deal struck between Tony Blair and Gordon Brown.
The prospect of a Treasury study on the impact of the euro has been used for six years as a device to stop members of the Government arguing in public over whether Britain should be in or out of the single currency.
Ministers who spoke out of turn on the subject were reminded that the current line was to say that they were not making a "running commentary" on whether Britain was ready to join until the Treasury had completed its assessment of Mr Brown's five economic tests.
Last week, the Scottish Secretary, Helen Liddell, came under heavy attack for making a pro-euro speech, claiming that joining the single currency would attract foreign investors to Scotland.
John Reid, the leader of the Commons, privately apologised to Downing Street after he claimed in an interview that joining the euro was a matter of "when" not "if".
The Health Secretary, Alan Milburn, who is reputed to be a strong euro-enthusiast, has never spoken on the subject since entering the Cabinet. Charles Clarke, whose pro-euro views are well known, has also kept silent on the subject since his appointment as Education Secretary.
A former Cabinet minister said yesterday: "They have had to keep a Trappist vow of silence. At their peril did they raise the single currency, because Brown and his people briefed against them.
"What you can expect after the tests have been published is that the whole Government will be a lot warmer towards the single currency."
Yesterday, most of the Cabinet spent the day reading through 2,500 pages of the Treasury study into the economic implications of joining the euro. Next week, ministers will meet Tony Blair and Gordon Brown one by one.
Mr Brown and Mr Blair are anxious to avoid having a vote in the Cabinet, fearing that the news would leak out.
The Deputy Prime Minister, John Prescott, who is one of the more eurosceptic Cabinet members, told BBC Radio 4's Today programme yesterday: "It's a collective voice. We are not doing anything different from the normal constitutional arrangements. The Prime Minister takes into account the views of members round the table."
There have been no formal votes in Cabinet since 1997, although they were sometimes held when Labour was in power in the 1960s and 1970s.Reuse content